Problem: Ben ate 1 slice of pizza. Nadia ate 5 slices. If Ben ate $\dfrac{1}{9}$ of the pizza, what fraction of the pizza is remaining?
Explanation: If 1 slice represents $\dfrac{1}{9}$ of the pizza, there must have been a total of 9 slices. $\text{fraction of pizza remaining} = \dfrac{\text{number of slices remaining}}{\text{number of slices total}}$ Together they ate 6 slices, which leaves 3 out of 9 slices remaining. There is $\dfrac{3}{9}$ of the pizza remaining.